Directional drilling apparatus with retrievable limiting device

ABSTRACT

A deflection tool is provided for use in the directional drilling of a well bore into the earth. The tool includes a lower tubular assembly pivotally mounted within an upper tubular assembly. I use, the upper assembly is coupled to the lower end of a string of drill pipe and the lower assembly is coupled to a downhole fluid motor unit which drives a rotary drill bit. Drilling fluid flowing down the drill string drives a piston and lever mechanism located in the upper tubular assembly for urging the lower tubular assembly to pivot relative thereto. when a zero or other less than maximum pivot angle is desired, a retrievable limiting probe is run into the deflection tool for setting a limiting plug which limits the extent of the pivotal movement. Different pivot angles are obtained by using limiting probes of different size.

United States Patent Primary Examinerlan A. Calvert Attorney-Jack W.Hayden ABSTRACT: A deflection tool is provided for use in thedirectional drilling of a well bore into the earth. The tool includes alower tubular assembly pivotally mounted within an upper tubularassembly, 1 use, the upper assembly is coupled to the lower end ofastring ofdrill pipe and the lower assembly is coupled to a downholefluid motor unit which drives a rotary drill bit. Drilling fluid flowingdown the drill string drives a piston and lever mechanism located in theupper tubular assembly for urging the lower tubular assembly to pivotrelative thereto. when a zero or other less than maximum pivot angle isdesired, a retrievable limiting probe is run into the deflection toolfor setting a limiting plug which limits the extent of the pivotalmovement. Different pivot angles are obtained by using limiting probesof different size.

82 Ill Ill SHEET 3 UF 4 A TTOKNE Y5 PATENIED DEC] 4 1971 PATENTEBnEmmn3,627,355

snmuuFa l l l EDWIN A. ANDERSON INVENTOR. \Lc w. 444 .4 BY 5 Pile/u!Bee.

4 T TORNE Y5 DIRECTIONAL DRILLING APPARATUS WITH RETRIEVABLE LIMITINGDEVICE BACKGROUND OF THE INVENTION This invention relates to directionaldrilling methods and apparatus for use in drilling well bores into theearth and is particularly useful in connection with drilling apparatuswherein the drill bit is driven by a downhole fluid motor.

In the drilling of oil and gas wells, the use of downhole fluid motorsfor rotating the drill bit is becoming more widespread. In a goodlynumber of such cases, it becomes desirable at some intermediate point inthe drilling process to change the direction in which the well bore isbeing drilled. It has been heretofore proposed to accomplish such changeby pulling the drill string from the well bore, inserting a bent tool orbent sub into the drill string intermediate the drill bit motor and thelower end of the drill pipe to impart a predetermined amount ofinclination to the motor-drill bit assembly, such inclination beinganywhere from k to 3. The drill string, motor, drill bit and permanentlybent sub are thereafter run back into the well bore. Drilling is thenrecommenced and the angular bend in the bent sub serves to urge thedrill bit in the desired new direction.

The use of a permanently bent sub has various disadvantages. Since thedownhole motor unit and drill bit extend a substantial distance belowthe bent sub, the lateral displacement caused by the presence of theangular bend in the bent sub substantially reduces the clearance betweenthe lower portion of the drill string and the wall of the well bore.Among other things, this means that greater care must be exercised whenrunning in or withdrawing the drill string from the well bore. Suchrunning in or withdrawal must be done at a slower rate of speed. Evenwith the exercise of care, the chances of damaging the mud cake on thewall of the well bore or of damaging the drill bit are increased. Thereis a much greater tendency for the drill bit to gouge and scrape thewall of the well bore. There is a much greater chance of the drill bitstriking a hard shoulder or ledge protruding into the well bore. Inaddition, the screwing and unscrewing of the pipe joints may be moredifficult because of the binding effect caused by the presence of thebent sub. For similar reasons, the orienting of the drill bit and motorunit in the desired compass direction may be rendered more difficult.Furthermore, the necessity of having to pull the drill string in orderto add or remove the bent sub requires a substantial expenditure of rigtime.

Another somewhat different method of changing the direction of a fluidmotor driven drill bit is described in U.S. Pat. No. 3,068,946, grantedto Messrs. Frisby and Cook on Dec. 18, I962. Frisby and Cook employ aso-called knuckle joint" which, at the appropriate moment in thedrilling operation, is connected into the drill string between the drillpipe and the fluid motor unit. Their knuckle joint is flexed or bent byapplying weight to the drill bit. Their knuckle joint, how ever, suffersfrom various disadvantages. For one thing it requires the withdrawal ofthe drill string from the well bore in order to insert or remove theknuckle joint at the appropriate points in the drilling process. Moreimportantly, perhaps, their device does not provide any positive controlover the flexing or bending of the knuckle joint. Weight can be appliedto the drill bit, but there is no positive assurance that the knucklejoint has flexed in the desired manner. Depending on its orientation, itmay have been limited in a straight or unflexed position. Also, sincetheir knuckle joint is free to pivot at any time, there is increaseddanger of hanging up the drill string when running it into the well borewith the knuckle joint in the string.

Since the present invention may be characterized as a modified form ofknuckle joint, it is pertinent to note that various forms of knucklejoints have been heretofore proposed for use in various types ofsubsurface well bore operations other than the actual drilling of thewell bore. Representative of these is the knuckle joint described inU.S. Pat. No. 2,680,483, granted to F. L. LeBus on June 8, I954. TheLeBus knuckle joint is intended for use as a fishing tool for recoveringdrill pipe from the well bore. As a probably consequence of thisdifferent use, it includes features which render it unsuitable for usein a drill string having a downhole fluid motor for driving the drillbit. For one thing, the LeBus device requires the running into the toolof a plug for plugging the fluid flow passage through the tool in orderto operate a piston mechanism which causes the tool to bend or knuckle.Such plugging of the flow passage would not allow sufficient flow ofdrilling fluid to enable proper operation of a downhole fluid motorlocated below the knuckle joint. In addition, the LeBus tool has nomeans for keeping the joint in a straight position for purposes ofdrilling a straight section of the well bore. Thus, assuming therestriction plug were not present, the use of the LeBus device wouldrequire the pulling of the drill string from the well bore in order toinsert and remove the knuckle joint before and after the drilling of acurved section of the well bore. Furthermore, since the LeBus knucklejoint is free to pivot when it is being run into the well bore, therewould be an increased likelihood of hanging up the drill strong whenrunning it into the well bore.

SUMMARY OF THE INVENTION It is an object of the invention, therefore, toprovide new and improved apparatus of directional drilling which iseasier, faster and more accurate than those heretofore proposed.

It is another object of the invention to provide new and improvedapparatus of directional drilling which minimizes the chances ofdamaging either the mud cake on the wall of the well bore or the drillbit.

It is a further object of the invention to provide a new and improveddeflection tool for use with fluid motor driven drill bits and which canbe connected in the drill string the entire time the well bore is beingdrilled.

It is an additional object of the invention to provide a new andimproved deflection tool for use with fluid motor driven drill bits andwhich can be limited in a positive manner at different desired angles(including a straight angle) at different stages in the drillingoperation without having to pull the drill string from the well bore.

In accordance with the invention, a deflection tool adapted to beconnected in a drill string for use in the directional drilling of awell bore comprises first tubular means and second tubular meanspivotally coupled thereto. The tool also includes fluid-responsive meanscarried within the tubular means and responsive to drilling fluidpressure in the tubular means for urging one of the tubular means topivot relative to the other. The tool further includes locking meansincluding a retrievable limiting device adapted for passage through thedrill string and into the tubular means for limiting the extent of suchpivotal movement.

For a better understanding of the present invention, together with otherand further objects and features thereof, reference is had to thefollowing description taken in connection with the accompanyingdrawings, the scope of the invention being pointed out in the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS Referring to the drawings:

FIGS. 1A and 1B are partial cross-sectional elevational views ofdifferent portions of a deflection tool constructed in accordance withthe present invention;

FIGS. 2, 3, and 4 are cross-sectional views taken along thecorrespondingly numbered section lines of FIGS. 1A and 1B;

FIG. 5 is a perspective'view of a guide bushing used in the FIG. 1Bportion of the tool;

FIG. 6 is a perspective view of a limiting plug used in the FIG. 1Bportion of the tool;

FIGS. 7A and 7B show the tool of FIGS. IA and 18 after it has beenoperated to put it in a bent position;

FIG. 8 is an enlarged view of the lower portion of the tool showing theprobe in nonseated position and the connector bushing restricting fluidflow;

FIG. 11 is a perspective view of a removable pivot stop block employedin the modified embodiment of FIG. 9.

DESCRIPTION OF THE FIRST EMBODIMENT Referring to FIGS. 1A and 1B of thedrawings, there is shown a first embodiment of a deflection tool adaptedto be connected in a drill string for use in the directional drilling ofa well bore'into the earth. These figures show the tool in its straightor undeflected position. FIG. 1A shows the upper portion of the tool,while FIG. 1B shows the lower portion of the tool.

As shown in FIGS. 1A and 1B, the deflection tool includes an uppertubular assembly 12 which is of an elongated cylindrical construction.This tubular assembly 12 includes a series of cylinders 13, 14 and 15which are threaded together in an overlapping end-to-end manner. Thetubular assembly 12 further includes a hollow cylindrical body member 16which is threaded onto the lower end of the lower cylinder 15. The uppertubular assembly 12 further includes a cylindrical pivot joint seatingmember 17 which is connected to the lower end of the body member 16 bymeans of an internally threaded connecting sleeve 18. Suitable toolcleanout plugs 19 are threaded into cooperating passageways at spacedpoints along the length of the tubular assembly 12. A top sub 20 isthreaded onto the upper end of the tubular assembly 12. The upper end(not shown) of the top sub 20 is provided with a threaded pin forconnecting the top sub 20 to the lower end of a nonmagnetic surveycollar which forms part of the drill pipe string. Top sub 20 includes aninterior longitudinal passage 21 having a reduced diameter lower portion22 and a shoulder 23 formed at the boundary between the portions ofdiflerent diameter.

The deflection tool further includes a lower tubular assembly 24pivotally coupled to the upper tubular assembly 12. As indicated in FIG.18, this lower tubular assembly 24 is pivotally mounted within the lowerportion of the upper tubular assembly 12. To this end, the lowerassembly 24 is provided with an enlarged spherical ball joint portion 25which is seated in a spherical socket 26 formed in the upper end of thepivot-joint-seating member 17 of the upper tubular assembly 12. Aretaining ring 27 holds the spherical ball 25 in place in the socket 26.The lower end 28 of the retaining ring 27 is provided with a sphericalcurvature which matches that of the spherical ball portion 25. A pair ofO-ring seals 29 are located in lateral grooves which encircle the ballportion 25, while a further O-ring seal 27a is located in a circulargroove in the lower part of body member 16 adjacent the retaining ring27. These seals 27a and 29 prevent leakage of the drilling fluid aroundthe ball and socket joint. The ball joint portion 25 can be suspended onits pivot axis in the manner described in the above-mentioned US. Pat.No. 2,680,483 to LeBus.

The lower tubular assembly 24 further includes an upper tubular portion30 located above the pivot axis (an axis passing through the center ofthe ball portion 25 at right angles to the plane of the paper in FIG.1B) and extending upwardly within the upper tubular assembly 12. Thoughthe length of tubular portion 30 may vary within limits, it preferablyshould be of suitable length to provide sufficient mechanical advantagefor insuring that the lower tubular assembly 24 is pivoted in thedesired manner.

The lower tubular assembly 24 further includes a lower tubular portion31 located below the pivot axis and extending downwardly and out of thelower end of the upper tubular assembly 12. The ball portion 25, theupper portion 30 and the lower portion 31 are formed from a single pieceof metal. A common longitudinal passageway 32 extends from one end tothe other of the lower tubular assembly 24 provided by these portions.Passageway 32 includes a reduced diameter lower portion 33, whichconstruction provides a shoulder 34 near the lower end of such passage32. Threadedly connected to the bottom end of the lower portion 31 ofthe lower assembly 24 is a bottom sub 35. Such bottom sub 35 includes atthe lower end thereof a threaded pin 36 which is adapted to be connectedto a downhole fluid motor unit which drives a rotary drill bit. Bottomsub 35 includes a longitudinal center bore or passage 37 for passing thedrilling fluid to the fluid motor unit located therebelow for purposesof energizing such unit.

As can be seen from FIG. 1B and the cross-sectional view of FIG. 4, theinterior of the lower portion of the upper tubular assembly 12 is shapedto allow pivoting of the lower assembly 24 in only one direction and tolimit the maximum extent of such pivotal movement. As there seen, thepivot-joint-seating member 17 is provided with a lower center bore 38which is cylindrical on the right-hand side thereof and which has formedin the left-hand side thereof a tapered recess 39 having a cylindricalcurvature for enabling the lower portion 31 of the lower assembly 24 tomove toward the left as viewed in FIG. 1B. As such, the tapered recess39 recedes from the longitudinal center axis of the pivot joint seatingmember 17 as it progresses in a downwardly direction. As will be betterappreciated hereinafter, the wall of the tapered recess 39 sets themaximum limit for the extent of pivotal movement of the lower tubularassembly 24. The deflection tool further includes fluid-responsive meanscarried within the upper tubular assembly 12 and responsive to drillingfluid pressure in such upper assembly 12 for producing a lateral thruston the upper portion 30 of the lower tubular assembly 24 for causingsuch assembly 24 to pivot about the pivot axis. Such fluid-responsivemeans includes a series of three longitudinally spaced pistons 40-42slidably mounted for longitudinal movement within the upper part of theupper assembly 12. Pistons 40-42 are of toroidal shape and, as such,include longitudinal center bores 44-46, respectively, which extendlongitudinally therethrough. Pistons 40-42 are interconnected by tubularstem members 48 and 49, the extremities of which are fitted intoenlarged portions of the center bores 44-46 of the pistons 40-42. Apiston-shaped ram 43 is mounted on a lower stem member 50 which isfitted into the lower enlarged portion of the center bore 46 of thelower piston 42. Ram 43 includes a longitudinal center bore 47 having ashoulder 47a which is engaged by a mating shoulder 500 on stem member 50whereby stem member 50 can drive 'ram 43 in a downwardly direction. Asindicated in FIG. 1B, the lower stem member 50 extends through the ram43 and a goodly distance into the upper portion 30 of the lower assembly24.

The interior of the upper portion of the upper assembly 12 and, moreparticularly, the interior of the cylinders 13-15 are constructed toprovide individual piston chambers 51-53 for the different pistons40-42, respectively. Chambers 51-53 are provided with fluid outlets55-57, respectively, at the lower extremities thereof for enabling thelower ends of these chambers to communicate with the lower pressure wellbore fluid exterior to the upper assembly 12. The upper ends of thepiston chambers 52 and 53 are adapted to receive the higher pressuredrilling fluid within the drill string by way of inlets 58 and 59 whichextend through the sidewalls of the stem members 48 and 49,respectively. The upper end of the upper piston 40 is exposed directlyto the drilling fluid leaving the lower passage 22 in the top sub 20. Aconcave recess 60 is provided in the top of the upper piston 40 forproviding an exposed piston surface even when the piston 40 is at theupper end of its range of movement. An inlet 61 is provided in lowerstem member 50 just above ram 43 for equalizing the pressure on the topand bottom sides thereof.

O-ring seals 62 provide fluid seals between the various pistons 40-42and their corresponding cylinder walls, between the various stem members48-50 and the center bores in the corresponding pistons and at thevarious other indicated points where it is desired to maintain afluidtight barrier. In addition to interconnecting the various pistons40-42 so that they work in unison with one another and are mechanicallycoupled to the ram 43, the stem members 48-50 also provide alongitudinal flow passage for conveying the drilling fluid through theupper tubular assembly 12 and into the lower tubular assembly 24. Thisflow passage provided by the stem members 48-50 is of reduced internaldiameter relative to the remainder of the longitudinal flow passageswithin the tubular assemblies 12 and 24.

In addition to the piston mechanism just described, the fluid responsivemeans further includes means for converting downward movement of thepistons into a lateral thrust on the upper portion 30 of the lowertubular assembly 24. This movement or force converting means includes acontrol lever 63 pivotally mounted within a tubular cage 64 which islocated within the upper tubular assembly 12 adjacent the upper end ofthe upper portion 30 of the lower tubular assembly 24. The cage 64 restson a shoulder 65 inside of the main body member 16. As indicated in thecross-sectional view of FIG. 3, the control lever 63 is of a U-shapedconstruction having side members 630 and 63b which straddle thecentrally located stern member 50. Pivot pins 66 and 67 pivotallyconnect these side members 63a and 63b to the cage 64. As indicated inFIG. 1B, the downwardly extending legs of the side members 630 and 63binclude contact faces 63c and 63d which engage oblique or slantedcontact faces 68 formed by cutting away a corner portion of the upperend of the tubular portion 30. Only the rearward contact face 630 ofcontrol lever 63 is visible in FIG. 1B, the nearer face 63d being infront of the cross section plane. The control lever 63 further includesan upper contact surface 63c which is adapted to be engaged by theunderside of the ram 43 during its downward movement. When ram 43 bearsagainst this contact surface 63e, it causes a pivoting of the controllever 63 which, in turn, causes the contact faces 63c and 63d to pushthe upper end of the tubular portion 30 of the pivotal assembly 24toward the right. in this manner, control lever 63 converts downwardmovement of the pistons 40-42 and ram 43 into a lateral thrust on theupper portion 30 of the pivotal assembly 24.

The deflection tool further includes limiting means including aretrievable limiting device 70 adapted for passage through the drillstring and into the tubular assemblies 12 and 24 for limiting the extentof the pivotal movement of the lower tubular assembly 24 relative to theupper assembly 12. In addition to the limiting device 70, this limitingmeans or limiting mechanism also includes a guide bushing 71 locatedwithin the center bore or passageway 32 of the lower portion of thepivotal assembly 24 and resting on the shoulder 34 formed therein. Aperspective view of this guide bushing 71 is shown in FIG. 5. As thereindicated, the guide bushing 71 includes a longitudinal center passage72 for receiving the lower end of the retrievable locking device 70 anda pair of C-shaped longitudinal side passages 73 and 74 for passingdrilling fluid past the guide bushing 71. Guide bushing 71 furtherincludes a lateral passage 75 running from the longitudinal centerpassage 72 to an opening 75a at one side of such guide bushing 71.

As indicated in FIG. 1B, the limiting mechanism further includeslaterally movable positioning means movably carried by the lower portion31 of the pivotal lower tubular assembly 24 and extending into thecenter bore 32 of such lower portion 31 for engagement by theretrievable limiting device 70. This laterally movable positioning meansis comprised of a positioning plug or limiting plug 76 which is slidablymounted in a lateral passage 77 through the sidewall of the lowerportion 31 and the lateral passage 75 in the guide bushing 71. Aperspective view of the limiting plug 76 is shown in H0. 6. Suchlimiting plug 76 includes an enlarged head 760 at one end thereof forengaging the tapered recess 39 formed in the wall of the upper tubularassembly 12. The opposite end of plug 76, which end is adapted to extendinto the guide bushing center bore 72, is provided with a cylindricalcurvature corresponding to the curvature of the retrievable limitingdevice 70. Opposite sides of plug 76 are cut to provide a pair of flatfaces 76 which cooperate with corresponding flat sidewalls 76b in theinner portion of the guide bushing lateral passage 75 for maintainingthe proper alignment for the cylindrically curved end surface 76b of theplug 76. As indicated in FIG. 1B, the length of the positioning orlimiting plug 76 is greater than the combined length of the lateralpassages 75 and 77 in the guide bushing 71 and the sidewall of the lowertubular portion 31. An O-ring seal 76d provides a fluid seal between thelimiting plug 76 and the wall of passage 77.

As seen in FIG. 1B, the retrievable limiting device 70 includes anelongated cylindrical probe member 80 having a cylindrical body portion80a and a tapered lower end portion 80b. A collar 800 is formed at anintermediate point on the probe member 80 for purposes of engaging thetop of the guide bushing 71 and thus limiting the downward movement ofthe probe member 80 through the guide bushing center passage 72. Theupper end of the probe member 80 is provided with a threaded connector81 which is threaded into the lower end of an enlarged connectingbushing 82 which, as will be seen, functions as a "tattletale plug.Threaded into the upper end of the connecting bushing 82 in a connectingrod 83 which extends upwardly through the interior of the tubular stemmembers 48-50 and is connected to the lower end of a retrievable fishingsub 84 located in the center passage of the deflection tool top sub20(F1G. 1A). As indicated in the cross-sectional view of FIG. 2, thefishing sub 84 includes laterally extending blades 84a which are seatedon the shoulder 23 intermediate the top sub passages 21 and 22. Thus,fishing sub 84 does not block the flow of drilling fluid. Fishing sub 84further includes an upper fishing neck 84b which is adapted to beengaged by a wire line overshot or retrieving device (not shown) whichmay be lowered through the drill string by means of a wire line forpurposes of withdrawing the limiting device 70 from the deflection tooland returning it to the surface of the earth. If the drilling medium ordrilling fluid is a liquid-drilling mud, then the limiting device 70 canbe placed in the deflection tool by dropping it through the drill stringin a free-falling go-devil manner. If, on the other hand, the drillingfluid is air, the limiting device 70 is lowered into place by means ofthe releasable wire line overshot device.

The diameter of the connecting bushing 82 is sized to substantiallyrestrict the flow of drilling fluid through the tubular stem members48-50 when such bushing 82 is within the stem members 48-50. As such,the diameter of the bushing 82 is slightly less than the inside diameterof the tubular stem members 48-50, the difference being such as toprovide a clearance on the order of, for example, one-sixteenth of aninch between the bushing 82 and the inner wall of the stem members48-50. Connecting bushing 82 thus serves as a tattletale device sincethe decrease in mud pump pressure when the connecting bushing 82 emergesfrom the bottom end of the lower stem member 50 serves to signal theoperator at the surface of the earth that the probe member 80 hasproperly entered the guide bushing 71. For this reason, the bushing 82is located above the locking portion 800 of the probe member 80 adistance such that it remains in the reduced diameter passage providedby the stem members 48-50 until the probe member 80 has moved asubstantial distance through the guide bushing center passage 72.

It is noted that the maximum cross-sectional area of the retrievablelimiting device 70 is substantially less than the cross-sectional areaof the interior of the lower tubular assembly 24. Thus, once theconnecting bushing 82 leaves the lower stem member 50, a substantialflow of drilling fluid is provided through the tubular assemblies 12 and24. The deflection tool is constructed so that such fluid flow is amplysufficient for purposes of driving a downhole fluid motor unit when suchmotor unit is connected to the bottom sub 35.

A scribe line 85 in the form of a narrow longitudinal groove is cut intothe exterior of the upper tubular assembly 12 at the lower end thereofon the side thereof to which the lower assembly 24 is adapted to pivot.Such scribe line 85 enables an accurate determination of the orientationof the line of deflection of the deflection tool with respect to anorienting device in a nonmagnetic directional survey collar which isconnected in the drill string immediately above the deflection tool.Such a directional survey collar is of known construction and cooperateswith a known type of wire line directional survey instrument which maybe lowered into such collar for determining the azimuth or compassdirection in which the orienting device is facing.

OPERATION OF THE FIRST EMBODIMENT Considering now the operating of theabove-described deflection tool, such tool is connected into a drillstring immediately above a downhole fluid motor unit which drives arotary drill bit. As a result of the novel manner of construction of thedeflection tool, it can remain in the drill string at all 'times duringthe drilling operation, even when drilling a straight portion of thehole. This will be assumed to be the case, namely, that the deflectiontool is connected into the drill string at the very beginning of thedrilling of the principal part of the well bore.

Since it is usually desired that the upper portion of the well bore be astraight hole (either vertical or on a slant), the deflection tool isinitially limited in its straight position. This is the position shownin FIGS. 1A and IB. The limiting is accomplished by placing theretrievable limiting device 70 in the deflection tool with the probemember 80 extending through the passage 72 in the guide bushing 71 andthe probe collar 80: resting on the top surface of such guide bushing71. In order to obtain the desired straight angle for the lower pivotalassembly 24, the diameter of the limiting portion 800 of the probemember 80 is just slightly less than the inside diameter of the centralpassage 72 in theguide bushing 71, a slight clearance being provided toprevent the probe member 80 from becoming stuck in the passage 72. Thepresence of this probe member 80 causes a maximum extension of thelimiting plug 76. Thus, the limiting plug 76 is forced against the wallof the tapered recess 39 which, in turn, forces the lower pivotalassembly 24 against the opposite wall of the passage 38 through thelower end of the pivot-joint-seating member 17. This locks thedeflection tool at a straight angle or in a straight position in apositive manner. With the deflection tool in such straight position, thedrill string is used to drill a straight portion of the well bore. Thedeflection tool is constructed to allow sufficient flow of drillingfluid at this time for properly operating the downhole fluid motor unit.

Assume now that at some later stage in the drilling operation it isdesired to change the direction in which the well bore is being drilled.This is accomplished by placing the deflection tool in a bent ordeflected position. Assuming for the moment that a maximum angle ofdeflection is desired, this is accomplished by removing the retrievablelimiting device 70 from the deflection tool and then operating thedrilling fluid or mud pump at the surface of the earth to increase thefluid pressure in the drill string. This produces the bent conditionillustrated in FIGS. 7A and 7B.

The removal of the limiting device 70 is accomplished by lowering a wireline overshot device through the drill string and allowing it to grabthe fishing neck 84b on the fishing sub 84 located at the top of theretrievable limiting device 70. The limiting device 70 is then withdrawnfrom the drill strong and retrieved at the surface of the earth.Referring to FIGS. 7A and 78, it is seen that with the probe member 80removed, the limiting plug 76 is free to slide back into the lateralpassages 75 and 77 in the guide bushing 71 and the wall of the tubularportion 31, respectively. Thus, the lower tubular assembly 24 is nowfree to pivot.

Such pivotal movement is produced in a positive manner by means of thepiston and control lever mechanism located in the upper portion of theupper tubular assembly 12. The pressure of the drilling fluid in theinterior of the drill string is increased, by increasing pump pressureat the earth's surface to urge the pistons 40-42 to move in a downwardlydirection. This causes the ram 43 to bear against the arm portion of thecontrol lever 63 and thus to cause such control lever 63 to pivot in acounterclockwise direction about the pivot pins 66 and 67. This causesthe contact faces 63c and 63d (latter not visible) to bear against theinclined contact faces 68 of the upper portion 30 of the pivotal tubularassembly 24. This produces a substantial lateral thrust on the upperportion 30, which portion functions like a lever arm to cause a pivotingof the entire lower tubular assembly 24. This forces the lower portion31 of the tubular assembly 24 against the tapered recess 39 in apositive manner, the limiting plug 76 being pushed into its retractedposition in the lateral passages 75 and 77.

Before the deflection tool is actually bent, it is necessary to rotateor orient the drill string so that the bent portion will point in theproper compass direction after it is deflected. This is accomplished bylowering a wire line directional survey instrument into the surveycollar located above the deflection tool for measuring the compassdirection in which the orienting device in the survey collar is facing.The survey instrument is then returned to the surface and its recordexamined. From this, together with the known angular relationshipbetween the orienting device in the survey collar and the scribe line onthe exterior of the deflection tool upper assembly 12, the presentcompass direction in which the scribe line 85 is facing is determined.The drill string is then rotated by the drilling rig rotary table theproper amount to obtain the desired orientation for the direction inwhich the lower end of the pivotal assembly 24 will pivot, suchdirection being denoted by the scribe line 85. Following suchorientation, the rotary table is limited and the drilling fluid pressureis increased to its normal operating or drilling level. This causes thedeflection tool to bend or deflect in the manner previously considered.Drilling of the well bore is then resumed, the bend angle in thedeflection tool causing the drill bit to follow a new course.

As long as the deflection tool remains bent, the drill bit will continueto follow a curved path. Usually, after a curved portion of a certainlength has been drilled, it is desired to resume the drilling of thewell bore on a straight path. With the present deflection tool, this canbe accomplished without the need of pulling the drill string from thewell bore. In order to return the deflection tool to a straightposition, all that is required is to run the retrievably limiting device70 back into the deflection tool. If the drilling medium is drillingmud, this is accomplished by dropping the limiting device 70 in agodevil fashion. If the drilling medium is air, the limiting device 70is lowered into the deflection tool by means of a releasable wire lineovershot device.

As the probe member 80 of the limiting device 70 enters the guidebushing 71, it forces the limiting plug 76 toward the left which, inturn, forces the pivotal assembly 24 toward the right. FIG. 8 shows thesituation as the tapered end of the probe member 80 begins its entryinto the guide bushing 71. Note that the connecting bushing 82 is stillin a tattletale position in the lower stem member 50. Consequently, ifthe drilling fluid or mud pump is operated with the bushing 82 in thisposition, the larger than normal fluid pressure indication at thesurface of the earth would indicate that the probe member 80 is notproperly seated in the guide bushing 71. In such a case, the mud pump isturned off to discontinue the hydraulic pump pressure. The drill stringis then slowly rotated through an angle of This enables the weight ofthe downhole fluid motor and drill bit to swing the pivotal lowertubular asembly 24 into a straight position at some point during suchrotation. Such straightening enables the probe member to descend intothe guide bushing 71 in the desired manner. Such occurrence is confirmedby the occurrence of normal drilling fluid pressure when the drillingfluid pump is again activated.

Complete entry of the probe member 80 into the guide bushing 71 movesthe longitudinal center axis of the lower tubular assembly 24 from amaximum deflected position, represented by reference line 86, to thestraight position represented by reference line 87, both reference linesbeing shown in FIG. 8. The maximum angle of deflection a may be on theorder of, for example 3.

It is a further feature of the present invention that the deflectiontool can be limited at any desired deflection angle intermediate thezero and maximum angles. A desired intermediate deflection angle isobtained by using a probe member 80 having a limiting portion 80a of theappropriate diameter. In other words, when the diameter of the limitingportion 80a is reduced, the limiting plug 76 assumes a partiallyextending position, thus limiting the pivotal movement of assembly 24resulting from the urging of the piston and lever mechanisms to avalueless than maximum but greater than zero.

By way of example, a straight portion of the well bore may first bedrilled using a limiting device 70 having a maximum diameter probemember 80. This produces a straight portion of the well bore. Thelimiting device 70 may then be retrieved from the well bore and themaximum diameter probe member replaced by a probe member of lesserdiameter. The limiting device 70 is then run back into the deflectiontool and a second portion of the well bore is drilled with thedeflection tool bent at an intermediate deflection angle. If, at a laterstage, it should be desired to further change the curvature of thecourse followed by the drill bit, the limiting device 70 can again beretrieved from the drill string and the second probe member replaced bya further probe member having a third size for its diameter. lf, ofcourse, the maximum deflection angle is desired, then drilling iscarried on with the retrievable limiting device 70 completely removedfrom the deflection tool.

DESCRIPTION OF THE SECOND EMBODIMENT Referring now to FIGS. 9-11, thereis shown a modified form of construction for the lower portion of thedeflection tool of FIGS. 1A and 18. Corresponding parts are identifiedby the same reference numerals as used in FIGS. 1A and 1B. Since a lowerortion of the upper tubular assembly is of a modified construction, suchupper tubular assembly is identified in FIG. 9 by the reference numeral12'.

The embodiment of FIG. 9 differs from the embodiment of FIGS. IA and 1Bin that a removable pivot stop block 90 is used in place of the taperedrecess 39 of the earlier embodiment for purposes of limiting the pivotalmovement. This pivot stop block 90 is mounted in a rectangular recess 91which is cut into the interior wall of pivot joint seating member 17 onone side thereof. An inner contact face 92 of the stop block 90 takesthe place of the contact face of the tapered recess 39 of the FIG. 13construction. Stop block 90 is held in place by means of a cap screw 93which extends through a lateral passage in the wall of thepivot-joint-seating member 17' and is threaded into a threaded passage94 in the stop block 90. As perhaps best seen in the cross-sectionalview of FIG. 10, a tapered semicylindrical recess 95 is also provided inthis second embodiment. The extreme left-hand portion of the inner wallof this recess 95 is to the left of the contact surface 92 of the stopblock 90. Hence, the stop block 90 and not the recess 95 now determinesthe maximum limit of deflection for the deflection tool.

A perspective view of the stop block 90 is shown in FIG. 11. By usingstop blocks of different thickness, different maximum limits can beestablished for the deflection angle. This provides a greater degree offlexibility in the use of the deflection tool.

While there have been described what are at present considered to bepreferred embodiments of this invention, it will be obvious to thoseskilled in the art that various changes and modifications may be madetherein without departing from the invention, and it is, therefore,intended to cover all such changes and modifications as fall within thetrue spirit and scope of the invention.

What is claimed is:

l. A deflection tool adapted to be connected in a drill string for usein the directional drilling of a well bore comprising:

first tubular means;

second tubular means pivotally coupled to the first tubular means;

fluid-responsive means carried within the tubular means and responsiveto drilling fluid pressure in the tubular means for urging one of thetubular means to pivot relative to the other;

and limiting means including a retrievable limiting device adapted forpassage through the drill string and into the tubular means for limitingthe extent of such pivotal movement while the limiting device is in thetubular means.

2. A deflection tool in accordance with claim 1 wherein the secondtubular means is pivotally mounted within the first tubular means andextends out one end thereof.

3. A deflection tool in accordance with claim I wherein thefluid-responsive means includes a piston slidably located in one of thetubular means.

4. A deflection tool in accordance with claim 1 wherein thefluid-responsive means includes a plurality of longitudinally spacedpistons located within one of the tubular means and interconnected bytubular stem means for enabling the pistons to work in unison with oneanother.

5. A deflection tool in accordance with claim 1 wherein:

the second tubular means includes an extended portion which extends intothe first tubular means;

the fluid-responsive means includes a longitudinally slidable pistonlocated in the first tubular means;

and the fluid-responsive means includes control lever means pivotallymounted within the first tubular means adjacent the end of such extendedportion for converting the longitudinal movement of the piston into alateral thrust on the end of such extended portion.

6. A deflection tool in accordance with claim 1 wherein the retrievablelimiting device includes a body portion the thickness of which controlsthe extent of the pivotal movement.

7. A deflection tool in accordance with claim 1 wherein the limitingmeans includes positioning means movably carried by one of the tubularmeans and engageable by the retrievable limiting device for establishingthe angular relationship between the two tubular means.

8. A deflection tool in accordance with claim 1 wherein the limitingmeans includes positioning means movable carried by the second tubularmeans and having a first portion for engaging the first tubular means onone side thereof and a second portion which extends into the center boreof the second tubu- Iar means for engagement by the retrievable limitingdevice for establishing the angular relationship between the two tubularmeans.

9. A deflection tool in accordance with claim 1 wherein:

the limiting means includes laterally movable positioning means carriedby one of the tubular means;

and the retrievable limiting device includes a body portion for engagingthe positioning means and moving it to a desired position.

10. A deflection tool in accordance with claim 1 wherein:

the first tubular means is located above the second tubular means;

the first tubular means includes interior longitudinal passage means ofreduced diameter;

the second tubular means includes receiving means for receiving theretrievable limiting device;

and the retrievable limiting device is of an elongated constructionadapted for passage through the reduced diameter passage means andincludes a limiting portion adapted to be seated in the receiving meansand an enlarged portion located relative to such limiting portion adistance such that it remains in the reduced diameter passage meansuntil the limiting portion has entered the receiving means, suchenlarged portion being sized to substantially reduce the flow ofdrilling fluid through the tool as long as it is within the reduceddiameter passage means.

tubular means and a lower portion located below the.

pivot axis and extending downwardly and out of the lower end of theupper tubular means; fluid-responsive means carried within the uppertubular means and responsive to drilling fluid pressure in the uppertubular means for producing a lateral thrust on the upper portion of thelower tubular means for causing the lower tubular means to pivot aboutthe pivot axis;

laterally movable positioning means movably carried by the lower tubularmeans and extending into the center bore of the lower tubular means;

and a retrievable limiting device adapted for passage through the drillstring and into the lower tubular means for engaging the laterallymovable positioning means and thereby controlling the angularrelationship between the two tubular means.

12. A deflection tool in accordance with claim 11 wherein the uppertubular means is adapted to be connected to the lower end of a string ofdrill pipe and the lower tubular means is adapted to be connected to adownhole fluid motor unit for driving a rotary drill bit.

13. A deflection tool in accordance with claim 11 wherein the interiorof the lower portion of the upper tubular means is shaped to allowpivoting of the lower tubular means in only one direction and to limitthe maximum extent of such pivoting movement.

14. A deflection tool in accordance with claim 11 wherein the fluidresponsive means includes:

longitudinally movable pis'ton means slidably located within the uppertubular means;

and means for converting downward movement of the piston means into alateral thrust on the upper portion of the lower tubular means.

15. A deflection tool in accordance with claim 14 wherein the movementconverting means comprises a control lever pivotally mounted within theupper tubular means adjacent the upper end of the upper portion of thelower tubular means and having an upper portion adapted to be engaged bythe underside of the piston means during its downward movement.

16. A deflection tool in accordance with claim 15 wherein the length ofthe upper portion of the lower tubular means is of suitable length toprovide a mechanical advantage for pivoting the lower tubular means.

17. A deflection tool in accordance with claim 11 wherein thefluid-responsive means includes:

a plurality of toroidal pistons located for longitudinal movement withinan upper portion of the upper tubular means; tubular stem meanscooperating with the center bores of the pistons for interconnecting thepistons in a spaced apart coaxial manner and of providing a central flowpassage through the upper portion of the upper tubular means; theinterior of the upper portion of the upper tubular means beingconstructed to provide individual piston chambers for the differentpistons; and means for converting downward force produced by the pistonsinto a lateral thrust on the upper portion of the lower tubular means;18. A deflection tool in accordance with claim 11 wherein the laterallymovable positioning means is carried within the upper tubular means bythe lower portion of the lower tubular means.

19. A deflection tool in accordance with claim 11 wherein the laterallymovable positioning means comprises a positioning plug slidably mountedin a lateral passageway extending through the wall of the lower tubularmember.

20. A deflection tool in accordance with claim 11 wherein thecross-sectional area of the retrievable limiting device is substantiallyless than the cross-sectional area of the interior of the lower tubularmeans for enabling a substantial flow of drilling fluid through thetubular means when the retrievable limiting device is in place in thelower tubular means.

21. A deflection tool in accordance with claim 11 wherein:

the retrievable limiting device includes an elongated cylindrical probemember forming at least the lower part thereof;

the tool includes a guide bushing located within the center bore of thelower tubular means and having a longitudinal center passage forreceiving the probe member, longitudinal side passages for passingdrilling fluid and a lateral passage running from the center passage toan opening at one side of such guide bushing;

the lower tubular means includes a lateral passage extending through thewall thereof and in alignment with the lateral passage in the guidebushing;

and the laterally movable positioning means comprises a positioning plugslidably mounted in the lateral passages in the guide bushing and thelower tubular means, the length of such positioning plug being greaterthan the combined length of such lateral passages.

22. A deflection tool in accordance with claim 21 wherein the guidebushing and the cooperating lateral passage in the lower tubular meansare located in a portion of the lower portion of the lower tubular meanswhich is within the upper tubular means.

23. A deflection tool in accordance with claim 11 wherein:

the upper tubular means includes an interior longitudinal passage meansof reduced diameter located at an upper location therein;

the lower tubular means includes receiving means for receiving theretrievable limiting device;

and the retrievable limiting device is of an elongated constructionadapted for passage through the reduced diameter passage means andincludes a lower limiting portion adapted to be seated in the receivingmeans and an enlarged portion located above such limiting portion adistance such that it remains in the reduced diameter passage meansuntil the limiting portion has entered the receiving means, suchenlarged portion being sized to substantially restrict the flow ofdrilling fluid through the tool as long as it is within the reduceddiameter passage means.

1:0; 3,627,356 Dated December 14, 1971 iiven e) EDWIN A. ANDERSON iscertified that error appears in the above-identified patent :.'.'.:lthe: Letters are hereby corrected as shown below:

"In the Abstract, line 10, change "when" to When-. ""5

Column 2, line 2, change "probably" to probable-. v Column 2, line 46,change "fluid-responsive" to -fluid responsive-. 1 Column 3, line 47,and column 4, line 15, change "pivot-joint= seating" to pivot jointseating-. Column 4, line 27, a new paragraph should begin with "Thedeflection tool" Y a i Column 4, lines 28 and 32, change"fluid-responsive" to fluid responsive. Column 4, line 61, change"sidewalls" to side walls. Column 4, line 74, change "fluidtight" tofluid tight--. Column 5, line 29, change "cross" to-cross- Column 5,line 66, change "sidewall" to side wall--.

Column 6, line 1, change "sidewalls" to side walls. Column 6, line 1,after "sidewalls" change "76b" to -75b--. Column 6, line 7, change"sidewall" to side wall. Column 6, lines 32 and 34, change "wire line"to wireline. Column 6, line 37, change "liquid-drilling" to liquiddrilling-. Column 6, line 41, change "wire line" to wireline. Column 7,line 6, change "wire line" to wirelinen Column 7, line 42, change"pivot-joint-seating" to pivot joint seating-. Column 8, lines 18 and51, change "wire .line" to -wireline. Column 9, line 10, change"extending" to -extended. Column 9, line 13, change "valueless" to valueless-. Column 9, line 52, change "pivot-joint-seating" to pivot jointseating-. Column 10, lines 4, 17, 20,- 28, and 30, change"fluid-responsive" to fluid responsive. Column 10, line 45, change"movable" to --movably-. Colunm ll, lines 11 and 53, change"fluid-responsive" to fluid responsive.

Signed and sealed this 2nd day of May 1972; J

(SEAL) Attest:

EDWARD M.FLEI'CHER,JR. ROBERT QOTTSCHALK Attesting Officer Commissionerof Patents

1. A deflection tool adapted to be connected in a drill string for usein the directional drilling of a well bore comprising: first tubularmeans; second tubular means pivotally coupled to the first tubularmeans; fluid-responsive means carried within the tubular means andresponsive to drilling fluid pressure in the tubular means for urgingone of the tubular means to pivot relative to the other; and limitingmeans including a retrievable limiting device adapted for passagethrough the drill string and into the tubular means for limiting theextent of such pivotal movement while the limiting device is in thetubular means.
 2. A deflection tool in accordance with claim 1 whereinthe second tubular means is pivotally mounted within the first tubularmeans and extends out one end thereof.
 3. A deflection tool inaccordance with claim 1 wherein the fluid-responsive means includes apiston slidably located in one of the tubular means.
 4. A deflectiontool in accordance with claim 1 wherein the fluid-responsive meansincludes a plurality of longitudinally spaced pistons located within oneof the tubular means and interconnected by tubular stem means forenabling the pistons to work in unison with one another.
 5. A deflectiontool in accordance with claim 1 wherein: the second tubular meansincludes an extended portion which extends into the first tubular means;the fluid-responsive means includes a longitudinally slidable pistonlocated in the first tubular means; and the fluid-responsive meansincludes control lever means pivotally mounted within the first tubularmeans adjacent the end of such extended portion for converting thelongitudinal movement of the piston into a lateral thrust on the end ofsuch extended portion.
 6. A deflection tool in accordance with claim 1wherein the retrievable limiting device includes a body portion thethickness of which controls the extent of the pivotal movement.
 7. Adeflection tool in accordance with claim 1 wherein the limiting meansincludes positioning means movably carried by one of the tubular meansand engageable by the retrievable limiting device for establishing theangular relationship between the two tubular means.
 8. A deflection toolin accordance with claim 1 wherein the limiting means includespositioning means movably carried by the second tubular means and havinga first portion for engaging the first tubular means on one side thereofand a second portion which extends into the center bore of the secondtubular means for engagement by the retrievable limiting device forestablishing the angular relationship between the two tubular means. 9.A deflection tool in accordance with claim 1 wherein: the limiting meansincludes laterally movable positioning means carried by one of thetubular means; and the retrievable limiting device includes a bodyportion for engaging the positioning means and moving it to a desiredposition.
 10. A deflection tool in accordance with claim 1 wherein: thefirst tubular means is located above the second tubular means; the firsttubular means includes interior longitudinal passage means of reduceddiameter; the second tubular means includes receiving means forreceiving the retrievable limiting device; and the retrievable limitingdevice is of an elongated construction adapted for passage through thereduced diameter passage means and includes a limiting portion adaptedto be seated in the receiving means and an enlarged portion locatedrelative to such limiting portion a distance such that it remains in thereduced diameter passage means until the limiting portion has enteredthe receiving means, such enlarged portion being sized to substantiallyreduce the flow of drilling fluid through the tool as long as it iswithin the reduced diameter passage means.
 11. A deflection tool adaptedto be connected in a drill string for use in the directional drilling ofa well bore comprising: upper tubular means; lower tubular meanspivotally mounted within the upper tubular means and having an upperportion located above the pivot axis and extending uPwardly within theupper tubular means and a lower portion located below the pivot axis andextending downwardly and out of the lower end of the upper tubularmeans; fluid-responsive means carried within the upper tubular means andresponsive to drilling fluid pressure in the upper tubular means forproducing a lateral thrust on the upper portion of the lower tubularmeans for causing the lower tubular means to pivot about the pivot axis;laterally movable positioning means movably carried by the lower tubularmeans and extending into the center bore of the lower tubular means; anda retrievable limiting device adapted for passage through the drillstring and into the lower tubular means for engaging the laterallymovable positioning means and thereby controlling the angularrelationship between the two tubular means.
 12. A deflection tool inaccordance with claim 11 wherein the upper tubular means is adapted tobe connected to the lower end of a string of drill pipe and the lowertubular means is adapted to be connected to a downhole fluid motor unitfor driving a rotary drill bit.
 13. A deflection tool in accordance withclaim 11 wherein the interior of the lower portion of the upper tubularmeans is shaped to allow pivoting of the lower tubular means in only onedirection and to limit the maximum extent of such pivoting movement. 14.A deflection tool in accordance with claim 11 wherein the fluidresponsive means includes: longitudinally movable piston means slidablylocated within the upper tubular means; and means for convertingdownward movement of the piston means into a lateral thrust on the upperportion of the lower tubular means.
 15. A deflection tool in accordancewith claim 14 wherein the movement converting means comprises a controllever pivotally mounted within the upper tubular means adjacent theupper end of the upper portion of the lower tubular means and having anupper portion adapted to be engaged by the underside of the piston meansduring its downward movement.
 16. A deflection tool in accordance withclaim 15 wherein the length of the upper portion of the lower tubularmeans is of suitable length to provide a mechanical advantage forpivoting the lower tubular means.
 17. A deflection tool in accordancewith claim 11 wherein the fluid-responsive means includes: a pluralityof toroidal pistons located for longitudinal movement within an upperportion of the upper tubular means; tubular stem means cooperating withthe center bores of the pistons for interconnecting the pistons in aspaced apart coaxial manner and for providing a central flow passagethrough the upper portion of the upper tubular means; the interior ofthe upper portion of the upper tubular means being constructed toprovide individual piston chambers for the different pistons; and meansfor converting downward force produced by the pistons into a lateralthrust on the upper portion of the lower tubular means.
 18. A deflectiontool in accordance with claim 11 wherein the laterally movablepositioning means is carried within the upper tubular means by the lowerportion of the lower tubular means.
 19. A deflection tool in accordancewith claim 11 wherein the laterally movable positioning means comprisesa positioning plug slidably mounted in a lateral passageway extendingthrough the wall of the lower tubular member.
 20. A deflection tool inaccordance with claim 11 wherein the cross-sectional area of theretrievable limiting device is substantially less than thecross-sectional area of the interior of the lower tubular means forenabling a substantial flow of drilling fluid through the tubular meanswhen the retrievable limiting device is in place in the lower tubularmeans.
 21. A deflection tool in accordance with claim 11 wherein: theretrievable limiting device includes an elongated cylindrical probemember forming at least the lower part thereof; the tool includes aguide bushing located within the ceNter bore of the lower tubular meansand having a longitudinal center passage for receiving the probe member,longitudinal side passages for passing drilling fluid and a lateralpassage running from the center passage to an opening at one side ofsuch guide bushing; the lower tubular means includes a lateral passageextending through the wall thereof and in alignment with the lateralpassage in the guide bushing; and the laterally movable positioningmeans comprises a positioning plug slidably mounted in the lateralpassages in the guide bushing and the lower tubular means, the length ofsuch positioning plug being greater than the combined length of suchlateral passages.
 22. A deflection tool in accordance with claim 21wherein the guide bushing and the cooperating lateral passage in thelower tubular means are located in a portion of the lower portion of thelower tubular means which is within the upper tubular means.
 23. Adeflection tool in accordance with claim 11 wherein: the upper tubularmeans includes an interior longitudinal passage means of reduceddiameter located at an upper location therein; the lower tubular meansincludes receiving means for receiving the retrievable limiting device;and the retrievable limiting device is of an elongated constructionadapted for passage through the reduced diameter passage means andincludes a lower limiting portion adapted to be seated in the receivingmeans and an enlarged portion located above such limiting portion adistance such that it remains in the reduced diameter passage meansuntil the limiting portion has entered the receiving means, suchenlarged portion being sized to substantially restrict the flow ofdrilling fluid through the tool as long as it is within the reduceddiameter passage means.